Trifluoromethane sulfonyl (—SO2CF3; triflyl, Tf) group is known as one of the strongest electron-accepting group, which has an action to increase the protonic acidity of its a position (J. Am. Chem. Soc. 96, 2275, 1974; Synthesis, 691, 1997; J. Fluorine Chem. 66, 301, 1994). For example, bis(triflyl)methane (CH2Tf2; pKa(H2O)=−1) (J. Am. Chem. Soc. 106, 1510, 1984) and phenylbis(triflyl)methane (PhCHTf2; pKa(MeCN)=7.83) (J. Org. Chem. 63, 7868, 1998) are strong acids that do not have the ability to oxidize. The inherent acidity ΔGacid (in gas condition) estimated by Koppel et al. is as follows (J. Am. Chem. Soc. 116, 3047, 1994): MeSO3H (315.0)<CH2Tf2 (310.5)<PhCHTf2 (310.3)<TfOH (299.5)<NHTf2 (291.8)<CHTf3 (289.0). These volatile crystalline solids are known to serve as a reactant when preparing a cationic organometallic dihydrido by protonating an organometallic hydrido (J. Am. Chem. Soc. 106, 1510, 1984; J. Chem. Soc., Chem. Commun. 1675, 1987; Inorg. Chem. 27, 1593, 1988; Inorg. Chem. 27, 2473, 1988; Organometallics 9, 1290, 1990). Based on these facts, it is expected that the steric and electronic effects of the aromatic group in the arylbis(triflyl)methane such as phenylbis(triflyl)methane and the like mentioned above, have a great effect on its Bronsted acidity and the property of their organometallic complex.
Heretofore, two methods have been known as a method for synthesizing the phenylbis(triflyl)methane mentioned above (J. Org. Chem. 38, 3358, 1973; Heteroatom Chem. 5, 9, 1994; J. Fluorine Chem. 64, 47, 1993; J. Fluorine Chem. 106, 139, 2000). One of the methods is a method wherein benzyl magnesium chloride is reacted with triflyl fluoride to synthesize phenylbis(triflyl)methane (40% yield) (J. Org. Chem. 38, 3358, 1973), and the other method is a method wherein light response between iodobenzene bis(triflylmethide) and benzene is conducted (61% yield) (Heteroatom Chem. 5, 9, 1994). The former requires a triflyl fluoride gas (bp=−21° C.) which is difficult to obtain, as a triflyl source, and the latter requires an excessive amount of benzene, a reactant, as a solvent. Moreover, in the case of the latter, arylbis(triflyl)methane is not formed when light response is conducted with allene, which has an electron-accepting group such as fluorobenzene.
Meanwhile, a method for synthesizing benzyl triflone has been reported by Hendrickson et al. (J. Am. Chem. Soc. 96, 2275, 1974; Synthesis, 691, 1997; J. Fluorine Chem. 66, 301, 1994). However, there was a problem that arylmethyl triflone could not be synthesized at a high yield when the aromatic group is an electron-accepting group and is inactivated (Synthesis, 691, 1997).
In addition, Lewis acid catalyst is known to be the most widely used catalyst in the aspect of organic synthesis. This Lewis acid catalyst associates with a specific functional group of an organic compound, forms a complex, and can be made to conduct a particular response only. The one that accepts an electron pair from which it reacts with is referred to as Lewis acid. Organic compounds generally have a functional group, and the functional group is usually a Lewis base, which attracts mutually with Lewis acid. The Lewis acid catalyst designed in this manner forms a complex with the functional group of the organic compound, and leads directly to the desired reaction. Due to this point, Lewis acid catalyst is also compared to an artificial enzyme. However, the reactivity and selectivity of the conventional Lewis acid catalyst was not so high compared to when enzyme was used, and was not sufficient. Therefore, a Lewis acid catalyst that has an excellent selectivity and reactivity, further capable of reacting under warm condition, has a good recovery rate and can be recycled, has been required.
Heretofore, a Lewis acid catalyst comprised of a compound shown by a general formula M[RfSO2—N—SO2Rf′]n or M[RfSO2—N—SO2Rf′]n.mH2O (wherein Rf and Rf′ represent a perfluoroalkyl group having 1 to 8 carbon atoms, M represents an element selected from alkaline metal, alkaline earth metal, transition metal, rare earth, aluminum, gallium, iridium, thallium, silicon, germanium, tin, lead, arsenic, antimony, bismuth, selenium and tellurium, n represents an integer of the same number as the valence of the corresponding metal, and m represents a natural number from 0.5 to 20) (Japanese Laid Open Patent Application No. 07-246338), and a Lewis acid catalyst shown by the following formula,
[wherein X represents —N(Tf1)Tf2 [wherein Tf1 represents —SO2Rf1, Tf2 represents —SO2Rf2 (wherein each of Rf1 and Rf2 independently represents a fluorine atom or a perfluoroalkyl group)], R1 represents a substituted or unsubstituted cyclopentadienyl group, —OR3 or —N(Tf3)R4, R2 represents a substituted or unsubstituted cyclopentadienyl group, —OR5 or —N(Tf4)R6 [wherein Tf3 represents —SO2Rf3, Tf4 represents —SO2Rf4 (wherein each of Rf3 and Rf4 independently represents a fluorine atom or a perfluoroalkyl group), each of R3, R4, R5 and R6 independently represents a lower alkyl group, or, R3 and R5, R3 and R6, R4 and R5 or R4 and R6 form together a bivalent group], M represents an element selected from alkaline earth metal, rare earth element, transition metal, boron, aluminum, gallium, indium, thallium, silicon, germanium, tin, lead, arsenic, antimony, bismuth, selenium or tellurium, n represents an integer of valence −2 of the corresponding M, and has at least one of —N(Tf1)Tf2, —N(Tf3)R4 or —N(Tf4)R6] (Japanese Laid Open Patent Application No. 09-57110), have been known as Lewis acid catalysts.
Aside from the examples mentioned above, there have been disclosures of highly active acid catalysts, including a highly active Lewis acid catalyst that can be used under the coexistence of water, comprising a metallic halide shown by a general formula M+(X1−)q (wherein M represents at least one metal selected from a group comprising elements from IIIA family to VB family of the periodic table, X1 represents a halogen atom, and q represents an integer that is identical to the valence number of M) and a quaternary type anion exchange resin (Japanese Laid Open Patent Application No. 09-262479), and an acid catalyst comprising a metallic salt of tris(perfluoroalkylsulfonyl)methide shown by the following formula [(RfSO2)3C]nM2 (however, Rf represents a perfluoroalkyl group having one or more carbon atoms, M2 represents an element selected from alkaline metal, alkaline earth metal, transition metal including rare earth, zinc, cadmium, aluminum, gallium, indium, thallium, silicon, germanium, tin, lead, arsenic, antimony, bismuth, selenium or tellurium. n represents an integer of the same number as the valence of M2) (Japanese Laid Open Patent Application No. 2000-219692).
Nafion (DuPont) is known as a solid catalyst having a super strong acidity. However, although it shows excellent swelling ability to water, alcohol and the like, it does not swell much in an aprotic organic solvent, which is frequently used in an organic reaction. If a solid catalyst having a super strong acidity can be used as a catalyst in a swelling condition, then it can be said that the solid catalyst is an excellent solid catalyst that exceeds Nafion. Due to this point, a solid catalyst that shows excellent swelling ability to organic solvents (for example, aromatic-based solvent, halogen-based solvent, ether-based solvent and the like) has been required. The object of the present invention is to provide a polymer-supported arylbis(perfluoroalkylsulfonyl)methane that is useful as a solid catalyst, which can be used in almost any reaction that progress with Bronsted acid or Lewis acid catalyst, has a high recovery rate, can be recycled easily, has versatility, and is also environment-friendly in that it does not contain metal; a method for producing said compound; catalysts such as Bronsted acid catalyst and the like comprising said compound; and a method for synthesizing organic compounds by using said catalysts.
The present inventors conducted a keen study to elucidate the object mentioned above. Sodium trifluoromethane sulfinate (TfNa) and trifluoromethane sulfonic acid anhydride (Tf2O) were used as an electrophilic reactant as a triflyl source to synthesize pentafluorophenylbis(triflyl)methane; said pentafluorophenylbis(triflyl)methane and LiOH.H2O were reacted in a diethylether to synthesize lithium pentafluorophenylbis(triflyl)methide; said lithium pentafluorophenylbis(triflyl)methide and 4-bromopolystyrene resin were reacted in a mixed solvent of benzene and THF under the presence of butyl lithium, the phenyl anion of the polystyrene resin was subjected to nucleophilic substitution reaction specifically in the para position of the pentafluorophenylbis(triflyl)methane to obtain a polystyrene-supported pentafluorophenylbis(triflyl)methane. It was found out that said polystyrene-supported pentafluorophenylbis(triflyl)methane serves as an excellent acid catalyst for acylation reaction of alcohol, aldol reaction, allylation reaction and the like, as a Bronsted acid or a Lewis acid catalyst. Thus, the present invention had been completed.